Indigo provides some advanced options for the various PowerLinc INSTEON interfaces. Select Configure… from the Interfaces→INSTEON/X10 Power Line menu, then (assuming you have a PowerLinc interface selected) click on the Interface Options… button. You'll see the Advanced PowerLinc Options dialog:
The first two options should always be checked by default - you really only want to disable those options if the Indigo Support team recommends it.
From this dialog, you can also perform some other link syncing operations:
Interfaces→INSTEON/X10 Power Line menu)